Fabrication and Mechanical Assembly

To begin the assembly of the device’s machinery, fol­low these steps:

1. It is assumed the power board as outlined is properly operating. Check for the absence of

corona in the high-voltage section. Corona dope is a coating that reduces elcctrical leak­age. Remove all sharp points and insulate with corona dope and so on.

Take a window screen and place it Hush against the objective end of the image lube. TUB 1. with a piece of clear scotch tape.

Secure the tube on the bench via modeling clay and temporarily connect it to the leads from the power board, as shown in Figure

23- 2. Observe the proper clearance of the leads and components. Darken the room and place a source of infrared filler light pointing toward the tube. (Use a flashlight preferably with an IR filter.) Note the tube glowing greenish and an image of the screen appearing either sharp or blurred. If the image is good and sharp, you are in luck. You may further improve the focusing by adding the 22- megohm resistors as shown in Figure 23-2.

This is usually noi necessary.

Fabricate EN1 from a 7-inch length of 2 Ъ inch ID schedule 40 PVC tubing. Note the hole adjaccnt to the HA 1 handle for feeding high-voltage wires to the tube from the power

board and */4-20 threaded holes are dimen­sioned in Figure 23-4 for securing and center­ing the image tube. These holes are located on a 120-degree radius.

4. Fabricate the HA1 handle from an 8-inch length of 1 ‘/2-inch ID schedule 40 PVC tubing. The tube must be shaped and fitted where it abuts to the EN1 main enclosure.

5. Fabricate the BRK 1 and 2 brackets from a half-inch-wide strip of 22-gauge aluminum as shown. Note the holes for #6 X ‘/4 sheet metal screws for securing the assembly together.

6. Fabricate TUB 1 from a 3 ‘/2-inch length of 2-inch ID schedule 40 PVC tubing for the objective lens. Note this is only 2 inches long when using the optional optics and“C orT” mount adapter fitting.

7. In order for TUB 1 to telescope into the main enclosure EN1, suitable cylindrical shims, САР2 and CAP3,must be fabricated. These are the 2 %-inch plastic caps. CAP2 has its end removed by cutting out the center using the wall of tubing as a guide for the knife. CAP3 has a smaller section cut out for LENSl. This method is cheap and works reasonably well. You obviously could substitute the pieces with properly fitted parts fabricated from alu­minum or plastic if you desire. This approach is more professional looking but can be much more costly.

8. The lens shown is a simple, uncorrected con­vex that is adequate for most infrared source viewing. It is not a quality viewing lens such as the optional 50 mm wide-angle or 75 mm tele­photo with the С mount threads. When using this lens, you should either create or purchase an adapter ring that will adapt to the lens threads and fit snugly into the enclosure. See CMT1.

9 The 1R16 image tube has preconnected leads The negative short lead attached to the objective end must have a 10-inch lead spliced to it. Insert the lube partway into the enclosure and snake the leads through the access hole. Position the tube and gently screw in the retaining screws by hand lo secure and center it.

10. Connect the leads from the tube to the power board as shown.

LI. lnscri the power board into the HAl handle. You will have to determine the access hole and drill for the switch Si once the board is secured in its final position. Wires should be long enough for the complete removal of the assembly when the handle is secured in place via the BRKI bracket. This allows any prelimi­nary adjustment or service. Leads may be shortened once proper operation is verified. Connect the battery to the power board and energize switch SI. If you did your homework, you will not have to readjust the focus taps or divider values. Once the operation is verified, check for any excessive corona and eliminate it. Position the board to switch SI adjacent to the access hole in the handle. It may be neces­sary to further secure the board in place via foam rubber pieces, a room temperature vul­canizing (RTV) adhesive, and so on. Slide a flexible rubber membrane over the access hole and insert the battery and cap САРІ.

12. Finally, assemble everything as shown in Fig­ure 23-5 and mount the infrared filtered flash­light. You will have to seal any light leaks using plumbers’ “monkey dung” or coax seal.

13. Adjust the objective and Ihen Ihe eyepiece for the clearest image.

Special Notes

The unit is shown with a built-in infrared source con­sisting of a common, everyday two-cell flashlight fit­ted with a special infrared filter. Any visible light leaks musl be sealed with electrician’s gunk, coax seal, or black liquid rubber.

This approach allows total flexibility in viewing sources not requiring infrared illumination as the light need not be energized or may even be removed. The light source may also be intensified by replacing the two D cells with an eight AA cell NiCad pack providing approximately 9 volts. A suitable lamp may be substituted, providing several times more illumi­nation. The lamp and batlery life will be greatly

Fabrication and Mechanical Assembly

Flashlight with infrared filter, sealed for light leaks

LTUB1

Note top tube positioning screws are cut flush when mounting integrated illuminator.

See step 13

Eyepiece can be a short focal-length magnifying lens

Optional rubber membrane for switch cover allowing activation

Fabrication and Mechanical Assembly

Figure 23-5 Final view

reduced as this approach is only intended for inter­mittent use. Note the now available halogen lamps are far more intense and make excellent infrared sources.

Longer-range viewing may be accomplished by using other, more intense sources such as higher – powered lights, auto headlamps, and so on. These must be fitted with the proper filters to be usable. A range of several hundred meters may be possible with these higher-powered sources. A source capable of allowing viewing from up to 500 feet is referenced in the project parts list.

Obtaining maximum performance and range from the system may require the optional lens system specified. The viewing of externally illuminated infrared sources will not require the integral infrared source.

You will note that this device is excellent for view­ing the output of most solid-state, gallium arsenide laser systems, LEDs, or any other source of infrared energy in the 9000 A spectrum. No internal infrared source is necessary when viewing these actual sources.

Table 23-1 5ee-in-the-dark prolECt

Ref. ft

Qty.

Description

DB#

Rl

1.5K, ‘/■’ – watt resistor (br-gr-red)

R2

15K, ’/-a – wait resistor (br-gr-or)

Cl

10 m/25-voIt electrical vertical capacitor (blue or green can)

C2

.047 m/50-volt plastic capacitor (473)

C3

47 m/100-volt plastic capacitor (474)

C4-15

12

270 pfd/3 Kv plastic disk capacitors

Dl-12

12

6 Kv. КЮ-nanosecond high-voltage avalanche diodes

01

MJE3055 NPN TO 220 case transistor

Tl

Special transformer info #28K077

#IU28K077

SI

Pushbutton switch

PBt

5Чі-> 1 Чг – inch perforated board wilh.1 X.1 grid

CL1

Snap battery clip

WR22

2

24-inch length of #22 vinyl hookup wire

WRHV20

12-inch. 2D Kv silicon wire

lRlfi

Image converter tuhe

#1UIR16

EN1

8- X 2 ’/p – inch schedule 40 gray PVC lube, created as shown

TUB1

3 Чг – inch length X 2-inch ID schedule 40 gray PVC

BRKI.2

2

9- X Чг – inch-thin aluminum strip as shown

САРІ

2-inch plastic cap for handle

CAP2.3

2

2 3/« – inch plaslic cap as shown

LENS1

45 x 63 double convex glass lens

SWl, 2

6

4* -20 X I-inch nylon screws

SW6

6

#6 X 4* – inch sheet metal screws

Optional parts

PCPBK

PCB

#PCPBK

CMT1

Prefabricated С mount adapter for EN1 enclosure

EPt

Small eyepiece

FIL6

6-inch glass infrared filter. 99.99 percent dark, for 0 beam light

HLRlO

200.000-candle-power infrared illuminator invisible to the naked eye, at 12 VDC

#HLR1U

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